I agree with you, kids are just kids and we shouldn't expect them to act as adults

Let me rephrase that; Behave as well mannered adults. I don't have human kids of my own, but I have helped raised a couple and have babysat for my family since I was a kid myself----Come to think of it, maybe that was the reason I took birth control sooooooo very seriously, I must have been turned off to the mommy thing since very young (???)
It is the toughest job you'll ever have, the most unappreciated and for which, sadly or fortunately, you WILL be judged even after you're gone

I totally understand. Kids have THEIR OWN personality and some are very strong willed, even as infants. I do try to remember that parenting skills differ and no matter how obnoxious the kid is, I try to think about what's going on at home that he/she feels he/she needs to act out in public. Kids, and us humans, for that matter, are so complex. Some act out because you hug them too much, others because you didn't hug them enough
Whatever it is, I try not to get frustrated when they do something I don't agree with (like kicking the back of my seat on the plane, at the movies, etc.) because they are just kids and seeing their eyes water would tear me apart, especially if they get punished because of me. So I basically understand the parents and the kid. Well, generally
Some parents are at fault, unfortunately, they are failing at the most important task. Very few are doing it on purpose, I think, but most really do try to raise them well. I just wish them well

You would get no weird looks from me, on the contrary, I applaud your efforts---it's not easy.